CN116457195A

CN116457195A - Polyolefin resin film and laminate using same

Info

Publication number: CN116457195A
Application number: CN202180077598.2A
Authority: CN
Inventors: 户松稚登; 西忠嗣; 山内祥惠
Original assignee: Toyobo Co Ltd
Current assignee: Toyobo Co Ltd
Priority date: 2020-11-19
Filing date: 2021-10-29
Publication date: 2023-07-18
Also published as: US20230415464A1; JPWO2022107575A1; KR20230105683A; TW202222587A; EP4249244A1; WO2022107575A1

Abstract

[ problem ] to provide: even when laminated with a substrate having high strength such as a biaxially oriented polyamide resin film, the polyolefin resin film exhibits high heat seal strength, and also has high bag-breaking resistance and pinhole resistance. [ solution ] A polyolefin resin film formed from a polypropylene resin composition containing a propylene-alpha olefin random copolymer, wherein the polyolefin resin film satisfies the following 1) to 5). 1) Comprising a sealing layer, a core layer and a lamination layer in sequence. 2) The content of the linear low-density polyethylene in the polypropylene resin composition constituting the sealing layer is 3 wt% or less. 3) The content of the linear low-density polyethylene in the polypropylene resin composition constituting the core layer and the laminate layer is 3 to 50 wt%. 4) The difference in the content of the linear low-density polyethylene in the polypropylene resin composition constituting the sealing layer and the core layer is 1 to 18 wt%, and the difference in the content of the linear low-density polyethylene in the core layer and the laminate layer is 1 to 18 wt%. 5) The content of the linear low-density polyethylene in the polypropylene resin composition constituting the core layer is greater than the content of the linear low-density polyethylene in the polypropylene resin composition constituting the sealing layer, and the content of the linear low-density polyethylene in the polypropylene resin composition constituting the laminate layer is greater than the content of the linear low-density polyethylene in the polypropylene resin composition constituting the core layer.

Description

Polyolefin resin film and laminate using same

Technical Field

The present invention relates to a polyolefin resin film. Further, the present invention relates to a laminate of a biaxially oriented film and at least 1 polymer selected from the group consisting of a polyamide resin film, a polyester resin film, and a polypropylene resin film.

Background

The package is manufactured as follows: the laminate is produced mainly by bringing a base film such as a polyamide resin film, a polyester resin film, or a polypropylene resin film into contact with a peripheral portion of a laminate of the polyolefin resin film or the like as a sealant, and performing heat-press bonding (heat sealing, hereinafter) at a temperature close to the melting point of the polyolefin resin film in a state where the surfaces of the polyolefin resin films are in contact with each other.

These packages are used for packaging and transporting various foods such as fresh foods, home dishes, and snacks. By using the package, the food can be efficiently delivered to the consumer, and the spoilage of the food can be delayed, thereby prolonging the flavor-enjoying period and avoiding the contamination of dust and the like during transportation and storage.

Since polypropylene resin films are inexpensive and packaging materials using the same are excellent in heat sealing property, they are widely used as heat sealing films.

The packaging material is required to have high heat seal strength and burst characteristics, and also is required to have few pinholes due to bending of the package during transportation, but when a film having high strength such as a biaxially oriented polyamide resin film is used as a base film, it is known that the heat seal strength and burst characteristics are improved in particular.

However, further improvement in performance is demanded, and improvement in burst characteristics has also been studied in the film for heat sealing.

Further, a technique of using a block polypropylene resin and adding a polyethylene resin is known (for example, refer to patent document 1).

However, the block polypropylene resin has a problem of poor transparency and a high heat seal initiation temperature.

Therefore, a technique of adding a linear low-density polyethylene to a polypropylene resin film is known (for example, refer to patent document 2).

However, when a base film having high strength such as a biaxially oriented polyamide resin film is laminated, there is a problem that the heat seal strength is reduced. This problem is not apparent when a polypropylene film having low strength is used as a base material.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2017-132186

Patent document 2: japanese patent laid-open No. 2020-75400

Disclosure of Invention

Problems to be solved by the invention

The purpose of the present invention is to provide: even when laminated with a base film having high strength such as a biaxially oriented polyamide resin film, the polyolefin resin film has high heat seal strength, and also has high burst characteristics and flex pinhole resistance.

The present inventors have conducted intensive studies to achieve the above object, and as a result, found that: the present invention has been completed in view of the above, and has been achieved by the present invention, in a polypropylene resin film formed from a polypropylene resin composition containing a propylene- α -olefin random copolymer, by controlling the dispersion state of a linear low-density polyethylene, a high heat seal strength is exhibited, and the burst characteristics and flex pinhole resistance are improved.

Namely, the present invention has the following configurations.

[1] A polyolefin resin film comprising a polypropylene resin composition containing a propylene-alpha olefin random copolymer,

the polyolefin resin film satisfies the following 1) to 5).

1) Comprising a sealing layer, a core layer and a lamination layer in sequence.

2) The content of the linear low-density polyethylene in the polypropylene resin composition constituting the sealing layer is 3 wt% or less.

3) The content of the linear low-density polyethylene in the polypropylene resin composition constituting the core layer and the laminate layer is 3 to 50 wt%.

4) The difference in the content of the linear low-density polyethylene in the polypropylene resin composition constituting the sealing layer and the core layer is 1 to 18 wt%, and the difference in the content of the linear low-density polyethylene in the core layer and the laminate layer is 1 to 18 wt%.

5) The content of the linear low-density polyethylene in the polypropylene resin composition constituting the core layer is greater than the content of the linear low-density polyethylene in the polypropylene resin composition constituting the sealing layer, and the content of the linear low-density polyethylene in the polypropylene resin composition constituting the laminate layer is greater than the content of the linear low-density polyethylene in the polypropylene resin composition constituting the core layer.

[2] The polyolefin resin film according to [1], wherein the Young's modulus of the polyolefin resin film in the longitudinal direction and the width direction is 400MPa or more and 800MPa or less.

[3] The polyolefin resin film according to [1] or [2], wherein the thickness of the polyolefin resin film is 15 μm or more and 80 μm or less.

[4]According to [1]]～[3]The polyolefin resin film according to any of the above, wherein the linear low-density polyethylene has a density of 910g/m ³ Above and 935g/m ³ The melt flow rate is 2.0g/10 min or more and 7.0g/10 min or less.

[5] The polyolefin resin film according to any one of [1] to [4], wherein the linear low-density polyethylene is a linear low-density polyethylene obtained by polymerizing ethylene containing ethylene derived from a plant.

[6] A laminate, comprising: [1] a polyolefin resin film and a biaxially oriented polyamide resin film as described in any one of [5 ].

[7] A laminate, comprising: [1] a polyolefin resin film and a biaxially oriented polyester resin film according to any one of [5 ].

[8] A package using the laminate of [6] or [7 ].

ADVANTAGEOUS EFFECTS OF INVENTION

The polyolefin resin film of the present invention is suitable for providing: a polyolefin resin film having high heat seal strength and high burst characteristics.

Detailed Description

The present invention will be described in detail below. The polyolefin resin film of the present invention is formed from a polypropylene resin composition containing a propylene-alpha olefin random copolymer.

(sealing layer)

(propylene-alpha olefin random copolymer)

In the present invention, the polypropylene resin composition constituting the sealing layer contains a propylene- α -olefin random copolymer in terms of heat seal strength.

Examples of the propylene- α -olefin random copolymer include a copolymer of propylene and at least 1 kind of α -olefin having 2 or 4 to 20 carbon atoms other than propylene. As the above-mentioned alpha-olefin monomer having 2 or 4 to 20 carbon atoms, ethylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, octene-1 and the like can be used.

The propylene- α -olefin random copolymer preferably uses ethylene as an α -olefin having 2 or 4 to 20 carbon atoms other than propylene in terms of heat sealability. In addition, the content is at least 1, and 2 or more kinds may be mixed and used as needed. Particularly suitable are propylene-ethylene-butene random copolymers in which propylene is the main monomer and a constant amount of ethylene is copolymerized with butene. In the present application, the monomer composition ratio constituting the random copolymer is described by referring to the order from more to less.

The lower limit of the Melt Flow Rate (MFR) of the propylene-alpha-olefin random copolymer is preferably 0.6g/10 min, more preferably 1.0g/10 min, still more preferably 1.2g/10 min. Uniformity of film thickness is sometimes impaired. The upper limit of the melt flow rate of the random copolymer is preferably 12.0g/10 min, more preferably 9.0g/10 min, still more preferably 8.0g/10 min.

Specifically, examples thereof include propylene-ethylene random copolymer (PrimePolymer Co., ltd., primepolypro F-724NPC, MFR7.0g/10 min at 230℃and 2.16kg, melting point 142 ℃), propylene-ethylene-butene random copolymer (Sumitomo chemical Co., ltd., friend Nobrene FL8115A, 230℃and 2.16kg, MFR7.0g/10 min at 2.16kg, melting point 148 ℃), propylene-ethylene-butene random copolymer (PrimePolymer Co., ltd., primepolypro F-794NV at 230℃and 2.16kg, MFR5.7g/10 min at 230℃and 134 ℃) and propylene-ethylene-butene random copolymer (Sumitomo chemical Co., friend Nobrene FL6745A, 230℃and MFR6.0g/10 min at 2.16kg, melting point 130 ℃).

The content of the propylene- α -olefin random copolymer in the polypropylene resin composition constituting the sealing layer is preferably 94% by weight or more, more preferably 97% by weight or more, still more preferably 99% by weight or more, and particularly preferably 100% by weight in terms of heat seal strength.

(propylene homopolymer)

In the present invention, the slidability can be improved by incorporating a propylene homopolymer into the polypropylene resin composition constituting the sealing layer. The propylene homopolymer to be used is not particularly limited, but from the viewpoint of antiblocking property, isotactic polypropylene is preferable.

The Melt Flow Rate (MFR) of the propylene homopolymer (measured at 230 ℃ C. Under a load of 2.16 kg) is not particularly limited, but is preferably 1.0g/10 min or more and 10.0g/10 min or less, more preferably 2.0 g/min or more and 8.0 g/min or less. This is because, when the viscosity is lower than 1g/10 min, the extrusion in the T die is difficult, whereas when the viscosity exceeds 10g/10 min, problems such as tackiness of the film and poor impact resistance (impact strength) of the film may occur. Specifically, examples include: sumitomo chemical propylene homopolymer FLX80E4 (MFR 7.5g/10 min, melting point 164 ℃).

The content of the propylene homopolymer in the polypropylene resin composition constituting the sealing layer is preferably 3% by weight or less, more preferably 2% by weight, further preferably 1% by weight or less, and particularly preferably 0% by weight in terms of heat seal strength. When the content of the polyethylene resin such as the linear low density polyethylene in the heat seal layer is large, compatibility between the heat seal layer and the polyethylene resin is poor, and therefore, heat seal strength may be lowered.

(Linear Low Density polyethylene)

By incorporating a linear low-density polyethylene into the polypropylene resin composition constituting the sealing layer, bending pinhole resistance can be improved. The linear low-density polyethylene can be produced by a production method such as a high-pressure method, a solution method, or a gas phase method. Examples of the linear low-density polyethylene include copolymers of ethylene and at least 1 alpha-olefin having 3 or more carbon atoms. The α -olefin may be generally referred to as an α -olefin, and is preferably an α -olefin having 3 to 12 carbon atoms such as propylene, butene-1, hexene-1, octene-1, and 4-methyl-1-pentene. Examples of the copolymer of ethylene and α -olefin include ethylene-hexene-1 copolymer, ethylene-butene-1 copolymer, and ethylene-octene-1 copolymer, and ethylene-hexene copolymer is preferable from the viewpoint of flex pinhole resistance.

(Linear Low Density polyethylene of plant origin)

The linear low density polyethylene may contain a plant-derived linear low density polyethylene obtained by polymerizing ethylene derived from a plant such as sugarcane with fossil fuel such as petroleum or an alpha olefin such as plant-derived ethylene.

The plant-derived linear low density polyethylene has substantially the same physical properties as the fossil-fuel-derived linear low density polyethylene, but has an effect of reducing carbon dioxide generated from the standpoint of carbon neutralization, and can suppress the greenhouse effect. The lower limit of the content of the plant-derived ethylene in the plant-derived linear low density polyethylene is preferably 50%, more preferably 80%. If the content is 50% or more, the effect of reducing carbon dioxide is good. The upper limit is preferably 98%, more preferably 96%. If it exceeds 98%, the ratio of copolymerized alpha-olefin decreases, and bending pinhole resistance decreases.

The lower limit of the MFR (measured at 190 ℃ C., 2.18 kg) of the linear low-density polyethylene is preferably 1.0g/10 min, more preferably 2.0g/10 min. And the upper limit is preferably 7.0 g/min, more preferably 5.0. When the content is within the above range, the compatibility with the polypropylene resin is good, and a high seal strength can be obtained.

The lower limit of the density of the linear low-density polyethylene is preferably 910kg/m ³ More preferably 913kg/m ³ . By setting to 910kg/m ³ Thus, good blocking resistance can be obtained. And an upper limit of 935kg/m ³ More preferably 930kg/m ³ . By a flow rate of 930kg/m ³ In the following, good burst characteristics can be obtained. Specifically, examples include: preparation of ethylene-hexene copolymer (Linear Low Density polyethylene of vegetable origin) SLH218 (MFR 2.3 g/min, density 916kg/m by Braskem) ³ Melting point 126 ℃ C.), sumitomo chemical ethylene-hexene copolymer (fossil fuel derived linear low density polyethylene) FV405 (MFR 4.0 g/min, density 923kg/m ³ Melting point 118℃), etc.

The content of the linear low-density polyethylene in the polypropylene resin composition constituting the sealing layer is preferably 3% by weight or less, more preferably 2% by weight, further preferably 1% by weight or less, and particularly preferably 0% by weight, in terms of heat seal strength.

The sliding property greatly depends on the addition amount of additives such as an antiblocking agent and an organic lubricant, and therefore, even if a linear low density polyethylene is added to the sealing layer, there is no change.

(additive)

The polyolefin-based resin composition constituting the sealing layer of the present invention may contain an anti-blocking agent. The anti-blocking agent may be 1 type, but when 2 or more kinds of inorganic particles having different particle diameters and shapes are blended, complex protrusions are formed in the irregularities on the film surface, and a higher anti-blocking effect can be obtained.

The anti-blocking agent to be added is not particularly limited, and spherical silica, amorphous silica, zeolite, talc, mica, alumina, hydrotalcite, aluminum borate and other inorganic particles, polymethyl methacrylate, ultra-high molecular weight polyethylene and other organic particles may be added.

The anti-blocking agent contained in the polypropylene resin composition constituting the sealing layer is preferably 3000ppm or less, more preferably 2500ppm or less, with respect to the polyolefin resin of the added layer. By setting the content to 3000ppm or less, the falling-off of the anti-blocking agent can be reduced. Further, it is preferably 500ppm or more, more preferably 1000ppm or more. By setting the content to 500ppm or more, good blocking resistance can be obtained.

The polyolefin resin composition may contain an organic lubricant. The laminated film has improved slidability and anti-blocking effect, and good handleability. For this reason, it is considered that the organic lubricant bleeds out and is present on the film surface, thereby exhibiting the lubricant effect and the release effect.

The organic lubricant preferably has a melting point of normal temperature or higher. The organic lubricant may be a fatty acid amide or a fatty acid ester.

Specifically, oleic acid amide, erucic acid amide, behenic acid amide, ethylene bis-oleic acid amide, hexamethylene bis-oleic acid amide, ethylene bis-oleic acid amide and the like are mentioned. These may be used alone, but a combination of 2 or more kinds is preferable because the slidability and anti-blocking effect can be maintained even in severe environments.

The organic lubricant in the polypropylene resin composition is preferably 1500ppm or less, more preferably 1000ppm or less, relative to the polyolefin resin. By setting the concentration to 1500ppm or less, adhesion is less likely to occur even when stored in a place exposed to high temperatures such as in a warehouse in summer. Further, it is preferably 200ppm or more, more preferably 250ppm or more. By setting the content to 200ppm or more, good slidability can be obtained.

The polyolefin resin composition constituting the sealing layer of the present invention may contain an appropriate amount of an antioxidant, an antistatic agent, an antifogging agent, a neutralizing agent, a nucleating agent, a colorant, other additives, an inorganic filler, and the like in any layer as required within a range not detrimental to the object of the present invention.

Examples of the antioxidant include a combination of a phenol-based and/or phosphite-based compound, and a single compound having a skeleton of a phenol-based and phosphite-based compound in one molecule. Examples of the neutralizing agent include calcium stearate.

(core layer)

(propylene-alpha olefin random copolymer)

In the present invention, the polypropylene resin composition constituting the core layer contains a propylene- α -olefin random copolymer in terms of heat seal strength.

The lower limit of the Melt Flow Rate (MFR) of the propylene-alpha-olefin random copolymer of the core layer is preferably 0.6g/10 min, more preferably 1.0g/10 min, still more preferably 1.2g/10 min. If it is less than 0.6g/10 minutes, uniformity of film thickness is sometimes impaired. The upper limit of the melt flow rate of the random copolymer is preferably 12.0g/10 min, more preferably 9.0g/10 min, still more preferably 8.0g/10 min.

The content of the propylene- α -olefin random copolymer in the polypropylene resin composition constituting the core layer is preferably 25% by weight or more, more preferably 40% by weight or more, still more preferably 60% by weight or more, particularly preferably 75% by weight or more, and particularly preferably 80% by weight or more, in view of heat seal strength. In terms of flex pinhole resistance, 97 wt% or less is preferable, 90 wt% or less is more preferable, and 85 wt% or less is still more preferable.

(propylene homopolymer)

In the present invention, the heat resistance can be improved by incorporating a propylene homopolymer into the polypropylene resin composition constituting the core layer. As the propylene homopolymer to be used, isotactic polypropylene having high crystallinity and suppressed deterioration of heat shrinkage is preferable.

The Melt Flow Rate (MFR) of the propylene homopolymer (measured at 230 ℃ C. Under a load of 2.16 kg) is not particularly limited, but is preferably 1.0g/10 min or more and 10.0g/10 min or less, more preferably 2.0 g/min or more and 8.0 g/min or less. This is because, when the viscosity is too high at less than 1g/10 min, extrusion in the T die is difficult, whereas when the viscosity exceeds 10g/10 min, problems such as tackiness of the film and poor impact resistance (impact strength) of the film occur. Specifically, there is, for example, sumitomo chemical propylene homopolymer FLX80E4 (MFR 7.5g/10 min, melting point 164 ℃).

The content of the propylene homopolymer in the polypropylene resin composition constituting the core layer is preferably 30% by weight or more, more preferably 40% by weight or more, in view of heat resistance. From the viewpoints of heat seal strength and burst resistance, it is preferably 50% by weight or less, more preferably 30% by weight or less, still more preferably 10% by weight or less, and particularly preferably 0% by weight.

The sliding property greatly depends on the addition amount of additives such as an anti-blocking agent and an organic lubricant, and therefore, even if a linear low-density polyethylene is added to the core layer, there is no change.

(Linear Low Density polyethylene)

By incorporating a linear low-density polyethylene into the polypropylene resin composition constituting the core layer, bending pinhole resistance can be improved. The linear low-density polyethylene can be produced by a production method such as a high-pressure method, a solution method, or a gas phase method. The linear low-density polyethylene may be a copolymer of ethylene and at least 1 kind of an alpha-olefin having 3 or more carbon atoms. The α -olefin may be generally referred to as an α -olefin, and is preferably an α -olefin having 3 to 12 carbon atoms such as propylene, butene-1, hexene-1, octene-1, and 4-methyl-1-pentene. Examples of the copolymer of ethylene and α -olefin include ethylene-hexene-1 copolymer, ethylene-butene-1 copolymer, and ethylene-octene-1 copolymer, and ethylene-hexene copolymer is preferable from the viewpoint of flex pinhole resistance.

(Linear Low Density polyethylene of plant origin)

The linear low density polyethylene may contain a plant-derived linear low density polyethylene obtained by polymerizing ethylene derived from a plant such as sugarcane with an alpha olefin such as petroleum-derived fossil fuel or plant-derived ethylene.

The lower limit of the MFR (measured at 190 ℃ C., 2.18 kg) of the linear low-density polyethylene is preferably 1.0g/10 min, more preferably 2.0g/10 min. And the upper limit is preferably 7.0 g/min, more preferably 5.0 g/min. When the content is within the above range, the compatibility with the polypropylene resin is good, and a high seal strength can be obtained.

The lower limit of the density of the linear low-density polyethylene is preferably 910kg/m ³ More preferably 913kg/m ³ . By setting to 910kg/m ³ Thus, good blocking resistance can be obtained. And an upper limit of 935kg/m ³ More preferably 930kg/m ³ . By setting to 930kg/m ³ In the following, good burst characteristics can be obtained. Specifically, examples include: preparation of ethylene-hexene copolymer (Linear Low Density polyethylene of vegetable origin) SLH218 (MFR 2.3 g/min, density 916kg/m by Braskem) ³ Melting point 126 ℃ C.), sumitomo chemical ethylene-hexene copolymer (fossil fuel derived linear low density polyethylene) FV405 (MFR 4.0 g/min, density 923kg/m ³ Melting point 118℃), etc.

The content of the linear low-density polyethylene in the polypropylene resin composition constituting the core layer is preferably 3% by weight or more, more preferably 8% by weight or more, still more preferably 12% by weight or more, and particularly preferably 15% by weight or more, in terms of flex pinhole resistance. In terms of heat resistance, it is preferably 50% by weight or less, more preferably 40% by weight or less, still more preferably 30% by weight or less, and particularly preferably 25% by weight or less.

(additive)

The polyolefin-based resin composition constituting the core layer of the present invention may contain an anti-blocking agent.

The antiblocking agent contained in the polypropylene resin composition constituting the core layer is preferably 3000ppm or less, more preferably 2500ppm or less, still more preferably 1000ppm or less, and particularly preferably 500ppm or less, with respect to the polyolefin resin of the added layer.

The polyolefin resin composition may contain an organic lubricant. The laminated film has improved slidability and anti-blocking effect, and the film has good handleability. For this reason, it is considered that the organic lubricant bleeds out and is present on the film surface, thereby exhibiting the lubricant effect and the release effect.

The polyolefin resin composition constituting the core layer of the present invention may contain an appropriate amount of an antioxidant, an antistatic agent, an antifogging agent, a neutralizing agent, a nucleating agent, a colorant, other additives, an inorganic filler, and the like in any layer as required within a range not detrimental to the object of the present invention.

(laminate layer)

(propylene-alpha olefin random copolymer)

In the present invention, the polypropylene-based resin composition constituting the laminate layer contains a propylene- α -olefin random copolymer in terms of heat seal strength.

The lower limit of the Melt Flow Rate (MFR) of the propylene-alpha-olefin random copolymer is preferably 0.6g/10 min, more preferably 1.0g/10 min, still more preferably 1.2g/10 min. If it is less than 0.6g/10 minutes, uniformity of film thickness is sometimes impaired. The upper limit of the melt flow rate of the random copolymer is preferably 12.0g/10 min, more preferably 9.0g/10 min, still more preferably 8.0g/10 min.

The content of the propylene- α -olefin random copolymer in the polypropylene resin composition constituting the laminate layer is preferably 25% by weight or more, more preferably 40% by weight or more, still more preferably 60% by weight or more, particularly preferably 75% by weight, and particularly preferably 80% by weight or more, in terms of heat seal strength. In view of flex pinhole resistance, it is preferably 90% by weight or less, more preferably 85% by weight or less, further preferably 80% by weight or less, particularly preferably 75% by weight or less, and particularly preferably 70% by weight or less.

(propylene homopolymer)

In the present invention, the heat resistance can be improved by incorporating a propylene homopolymer into the polypropylene resin composition constituting the laminate layer. As the propylene homopolymer to be used, isotactic polypropylene having high crystallinity and suppressed deterioration of heat shrinkage is preferable.

The content of the propylene homopolymer in the polypropylene resin composition constituting the laminate layer is preferably 30% by weight or more, more preferably 40% by weight or more, and particularly preferably 50% by weight or more in view of heat resistance. In terms of heat seal strength and flex pinhole resistance, it is preferably 70% by weight or less, more preferably 65% by weight or less, and still more preferably 60% by weight or less.

(Linear Low Density polyethylene)

By incorporating a linear low-density polyethylene into the polypropylene resin composition constituting the laminate layer, bending pinhole resistance can be improved. The film surface layer also contains a linear low density polyethylene, and thus the flex pinhole resistance is markedly improved, compared with the case where only the core layer contains a linear low density polyethylene.

The linear low-density polyethylene can be produced by a production method such as a high-pressure method, a solution method, or a gas phase method. Examples of the linear low-density polyethylene include copolymers of ethylene and at least 1 alpha-olefin having 3 or more carbon atoms. The α -olefin may be generally referred to as an α -olefin, and is preferably an α -olefin having 3 to 12 carbon atoms such as propylene, butene-1, hexene-1, octene-1, and 4-methyl-1-pentene. Examples of the copolymer of ethylene and α -olefin include ethylene-hexene-1 copolymer, ethylene-butene-1 copolymer, and ethylene-octene-1 copolymer, and ethylene-hexene copolymer is preferable from the viewpoint of flex pinhole resistance.

(Linear Low Density polyethylene of plant origin)

The lower limit of the density of the linear low-density polyethylene is preferably 910kg/m ³ More preferably 913kg/m ³ . By setting to 910kg/m ³ Thus, good blocking resistance can be obtained. And an upper limit of 935kg/m ³ More preferably 930kg/m ³ . By a flow rate of 930kg/m ³ Thus, good burst resistance can be obtained. Specifically, examples include: preparation of ethylene-hexene by BraskemCopolymer (plant derived Linear Low Density polyethylene) SLH218 (MFR 2.3 g/min, density 916 kg/m) ³ Melting point 126 ℃ C.), sumitomo chemical ethylene-hexene copolymer (fossil fuel derived linear low density polyethylene) FV405 (MFR 4.0 g/min, density 923kg/m ³ Melting point 118℃), etc.

The content of the linear low-density polyethylene in the polypropylene resin composition constituting the laminate layer is preferably 3% by weight or more, more preferably 8% by weight or more, still more preferably 15% by weight or more, particularly preferably 20% by weight or more, and most preferably 25% by weight or more, in terms of flex pinhole resistance. In terms of heat resistance and heat seal strength, it is preferably 50% by weight or less, more preferably 40% by weight or less, and still more preferably 30% by weight or less.

The sliding property greatly depends on the addition amount of additives such as an antiblocking agent and an organic lubricant, and therefore, even if a linear low-density polyethylene is added to the laminate layer, there is no change.

(additive)

The polyolefin-based resin composition constituting the laminate layer of the present invention may contain an anti-blocking agent. The anti-blocking agent may be 1 type, but when 2 or more kinds of inorganic particles having different particle diameters and shapes are blended, complex protrusions are formed in the irregularities on the film surface, and a higher anti-blocking effect can be obtained.

The antiblocking agent contained in the polypropylene resin composition constituting the laminate layer is preferably 3000ppm or less, more preferably 2500ppm or less, still more preferably 1000ppm or less, particularly preferably 500ppm or less, and most preferably 200ppm or less, with respect to the polyolefin resin of the added layer. By setting the amount to 3000ppm or less, the release of the anti-blocking agent on the surface of the laminate layer can be reduced.

The polyolefin resin composition may contain an organic lubricant. The laminated film has improved slidability and anti-blocking effect, and good film handling. For this reason, it is considered that the organic lubricant bleeds out and is present on the film surface, thereby exhibiting the lubricant effect and the release effect.

The organic lubricant in the polypropylene resin composition is preferably 1500ppm or less, more preferably 1000ppm or less, particularly preferably 500ppm or less, and particularly preferably 200pp or less, based on the polyolefin resin. By setting the concentration to 1500ppm or less, adhesion is less likely to occur even when stored in a place exposed to high temperatures such as in a warehouse in summer.

The polyolefin resin composition constituting the laminate layer of the present invention may contain an appropriate amount of an antioxidant, an antistatic agent, an antifogging agent, a neutralizing agent, a nucleating agent, a colorant, other additives, an inorganic filler, and the like in any layer as required within a range not detrimental to the object of the present invention.

(polyolefin resin film)

The polyolefin resin film of the present invention has a laminated structure, and comprises a sealing layer, a core layer, and a laminated layer in this order.

The sealing layer and the lamination layer are layers located on the surface side of the film with the core layer located therebetween.

The laminate layer is a layer suitable for bonding a base film such as a biaxially oriented polyamide film, and is preferably actually laminated to the base film via an adhesive resin.

The sealing layer is a layer suitable for producing a package by superposing 2 sheets of the laminate so that the polyolefin resin film of the obtained laminate is inside, and heat-sealing the laminate.

The polyolefin resin film of the present invention preferably has a difference in the content of the linear low-density polyethylene in the polypropylene resin composition constituting the sealing layer and the core layer of 1% by weight or more and 18% by weight or less. The concentration difference between the linear low-density polyethylene of the sealing layer and the core layer is more preferably 15% by weight or less, still more preferably 10% by weight or less, and particularly preferably 8% by weight or less. By setting the difference between the contents to 18 wt% or less, the interlayer strength at the interface between the sealing layer and the core layer can be maintained high, and a high heat seal strength can be obtained.

The polyolefin resin film of the present invention preferably has a difference in the content of the linear low-density polyethylene in the polypropylene resin composition constituting the core layer and the laminate layer of 1% by weight or more and 18% by weight or less. The concentration difference between the linear low-density polyethylene of the sealing layer and the core layer is more preferably 15% by weight or less, still more preferably 10% by weight or less, and particularly preferably 8% by weight or less. By setting the difference between the contents to 18 wt% or less, the interlayer strength at the interface between the sealing layer and the core layer can be maintained high, and a high heat seal strength can be obtained.

The polyolefin resin film of the present invention preferably has a content of the linear low-density polyethylene in the polypropylene resin composition constituting the core layer greater than a content of the linear low-density polyethylene in the polypropylene resin composition constituting the sealing layer, and a content of the linear low-density polyethylene in the polypropylene resin composition constituting the laminate layer greater than a content of the linear low-density polyethylene in the polypropylene resin composition constituting the core layer. In this way, the linear low density polyethylene is easily dispersed in the film uniformly, and the film is advantageous in terms of flex pinhole resistance. In addition, the ratio of the polypropylene resin to the resin close to the heat cover is large, and thus a high heat seal strength can be obtained.

Further, the propylene- α -olefin random copolymer having a low melting point is used for the sealing layer, and the propylene- α -olefin random copolymer having a high melting point is used for the core layer and the laminate layer, so that the heat seal strength can be improved, and the heat resistance and the pinhole resistance can be further improved.

The surface of the laminated layer of the polyolefin resin film of the present invention is preferably activated by corona treatment or the like. Thus, the lamination strength with the base film is improved.

The lower limit of the thickness of the polyolefin resin film of the present invention is preferably 15. Mu.m, more preferably 20. Mu.m, and still more preferably 25. Mu.m. If it is 15 μm or more, heat seal strength and burst characteristics are easily obtained.

The upper limit of the film thickness is preferably 80 μm, more preferably 70 μm, still more preferably 65 μm, still more preferably 60 μm, particularly preferably 50 μm. If the thickness is 80 μm or less, the film is not excessively strong in stiffness, and is easy to process, and a suitable package can be easily produced.

(Process for producing polyolefin resin film)

The method for molding the polyolefin resin film of the present invention may use, for example, an inflation method or a T-die method, but the T-die method is preferable for improving transparency. Since the cooling medium of the inflation system is air and the T-die system uses a cooling roll, the production method is advantageous for increasing the cooling rate. By increasing the cooling rate, crystallization of the unstretched sheet can be suppressed, and therefore, transparency becomes advantageous. For this reason, a sheet in which the T die side is unoriented is preferable.

Raw materials of the polypropylene resin composition for the sealing layer, the core layer and the laminate layer were mixed, and melt-mixed and extruded in respective extruders, and a laminate sheet of the sealing layer, the core layer and the laminate layer melted from the T die was cast on a cooling roll to obtain an unoriented sheet. The lower limit of the temperature of the cooling roll is preferably 15 ℃, more preferably 20 ℃. If the temperature is lower than the above, dew condensation occurs on the cooling roll, and the adhesion may be insufficient. The upper limit of the cooling roll is preferably 60℃and more preferably 50 ℃. If the amount exceeds the above, transparency may be deteriorated.

By adding the pellets to be reused for the semi-finished product or the produced product film produced in the production process to the core layer, the resin can be reused without impairing the heat seal strength, the flex pinhole resistance, and the bag breakage resistance.

(Properties of polyolefin resin film)

(haze)

The lower limit of the haze of the polyolefin resin film of the present invention is preferably 1.0%, more preferably 2.0%, further preferably 2.5%, particularly preferably 3.0%. If the content is 1.0% or more, the surface roughness of the film is not extremely small, and thus, the inner surface blocking of the package is less likely to occur.

The upper limit of the haze is preferably 20.0%, more preferably 15.0%, further preferably 10.0%, still more preferably 8% or less, particularly preferably 6% or less. If it is 20.0% or less, visibility of the package is easily obtained. The linear low density polyethylene has high crystallinity and tends to increase in haze, but if it is added in the above preferable range, the increase in haze is suppressed.

(coefficient of static friction)

The upper limit of the static friction coefficient of the polyolefin resin film of the present invention is preferably 0.70, more preferably 0.50, and still more preferably 0.40. If the amount is 0.70 or less, the surfaces which are not present when filling the package with food or when unsealing are likely to slide, and the opening is good.

The lower limit of the static friction coefficient alone is preferably 0.10, more preferably 0.15, further preferably 0.20, still further preferably 0.25, particularly preferably 0.30. If the amount is 0.10 or more, the film in a roll form is less likely to undergo roll breakage during transportation.

(Young's modulus)

The lower limit of Young's modulus (in the longitudinal direction) of the polyolefin resin film of the present invention is preferably 200MPa, more preferably 300MPa, still more preferably 400MPa, still more preferably 500MPa, particularly preferably 600MPa. If the pressure is less than 200MPa, the stiffness is too low and the processing is sometimes difficult. The upper limit of Young's modulus (in the longitudinal direction) is preferably 1000MPa, more preferably 800MPa, still more preferably 750MPa. Films exceeding 1000MPa are brittle, and thus the burst pouch property may be deteriorated.

The lower limit of Young's modulus (width direction) of the polyolefin resin film of the present invention is preferably 200MPa, more preferably 300MPa, still more preferably 400MPa, still more preferably 500MPa, particularly preferably 600MPa. If the pressure is less than 200MPa, the stiffness is too low and the processing is sometimes difficult. The upper limit of Young's modulus (width direction) is preferably 1000MPa, more preferably 800MPa, and still more preferably 750MPa. Films exceeding 1000MPa are brittle, and thus the burst pouch property may be deteriorated. If a small amount of linear low density polyethylene is added to the polypropylene resin film, the Young's modulus increases.

(impact Strength)

The lower limit of the impact strength of the polyolefin resin film of the present invention is preferably 0.20J, more preferably 0.25J, still more preferably 0.30J, and still more preferably 0.55J. By setting the value to 0.20J or more, the package can be improved in the resistance to falling and bag breakage. The impact strength is sufficient if it is 1.0J. Impact strength is greatly dependent on thickness, and molecular orientation of the film. In addition, impact strength is not necessarily related to resistance to falling and breaking.

(accelerated blocking Strength)

The lower limit of the accelerated blocking strength of the polyolefin resin film of the present invention is preferably 20mN/70mm, more preferably 30mN/70mm, still more preferably 36mN/70mm. If the ratio is 20mN/70mm or more, the film tends to have a stiff feel. The upper limit of the accelerated blocking strength is preferably 100mN/70mm, more preferably 80mN/70mm, still more preferably 70mN/70mm, particularly preferably 60mN/70mm. If the ratio is 100mN/70mm or less, blocking is less likely to occur on the inner surface of the package. If a linear low density polyethylene is added to the core layer or the laminate layer, deterioration of the accelerated blocking strength is suppressed.

(puncture Strength)

The lower limit of the puncture strength of the polyolefin resin film of the present invention alone is preferably 1.0N, more preferably 1.2N, still more preferably 1.5N, and still more preferably 1.7N. If the thickness is 1.0 μm or more, the puncture pinhole resistance of the laminate becomes good. The puncture strength is extremely excellent if it is 5.0N/. Mu.m, and is sufficiently high if it is 3.0N/. Mu.m. The puncture strength greatly depends on the orientation of the film, and therefore, only by virtue of the change in resin, is not changed so much.

(film plane orientation factor)

The lower limit of the plane orientation factor of the film is preferably 0.000, more preferably 0.001. It is difficult to manufacture a film lower than the above. The upper limit of the plane orientation of the film is 0.010, more preferably 0.008, and still more preferably 0.006 or less. If the thickness is not less than the above, the film may be unevenly stretched, and the thickness uniformity may be deteriorated.

(Heat seal initiation temperature)

The lower limit of the heat sealing initiation temperature of the polyolefin resin film of the present invention is preferably 110℃and more preferably 120 ℃. When the temperature is 110 ℃ or higher, the stiffness is high, and the handling is easy. The upper limit of the heat-seal initiation temperature is 150 ℃, more preferably 140 ℃, still more preferably 130 ℃. If the temperature is 150 ℃ or lower, the package can be produced at a high speed, which is economically advantageous. The heat seal initiation temperature is greatly affected by the melting point of the sealing layer. Therefore, if the linear low density polyethylene is used for the core layer and the laminate layer, the variation in heat sealing temperature is suppressed.

(wetting tension)

The lower limit of the wetting tension of the face of the polyolefin resin film of the present invention laminated with at least 1 film selected from the group consisting of a polyamide resin film, a polyester resin film, and a polypropylene resin film is preferably 30mN/m, more preferably 35mN/m. If it is 30mN/m or more, the lamination strength is not liable to be lowered. The upper limit of the wetting tension is preferably 55mN/m, more preferably 50mN/m. If the film is 55mN/m or less, adhesion of the films to each other is less likely to occur when the polyolefin resin film is wound around a roll.

(laminate Structure and manufacturing method)

The laminate using the polyolefin resin film of the present invention is a laminate of at least 1 film selected from the group consisting of a polyamide resin film, a polyester resin film, and a polypropylene resin film, using the polyolefin resin film as a sealant. In addition, as a known technique, a substrate film which is coated or vapor-deposited for the purpose of imparting adhesiveness and barrier properties may be used, or a structure in which aluminum foil or the like is further laminated may be used.

Specifically, examples thereof include biaxially stretched (polyethylene terephthalate) PET film/aluminum foil/sealant, biaxially stretched (polyethylene terephthalate) PET film/biaxially stretched nylon film/sealant, biaxially stretched polypropylene film/sealant, biaxially stretched (polyethylene terephthalate) PET film/biaxially stretched nylon film/aluminum foil/sealant, and the like.

The biaxially stretched nylon film has higher strength than other base films, and the laminate has higher seal strength.

The biaxially stretched nylon film to be used is preferably a biaxially stretched film made of nylon 6 or nylon 66, and the thickness thereof is preferably in the range of 15 to 30. Mu.m.

The use of the polyolefin resin film of the present invention as a sealant can improve heat sealability and bag-burst characteristics and pinhole resistance of the laminate.

The lamination method may be a known method such as a dry lamination method or an extrusion lamination method, but may be any lamination method.

The characteristics of the laminate will be described.

(bending pinhole resistance)

The bending resistance can be measured by Gelbo pinhole evaluation. The upper limit of the number of pinholes after 1000 bending at 1℃of the laminate of the present invention is preferably 35, more preferably 30, further preferably 25, particularly preferably 20, and most preferably 18. If the number of the plastic film is 35 or less, pinholes are less likely to occur due to bending shock during transportation of the package. The number of pinholes is very high if it is about 10.

(puncture Strength)

The lower limit of the puncture strength of the laminate of the present invention is preferably 10N, more preferably 12N, and further preferably 14N. If the number is 10N or more, pinholes are less likely to occur when the package contacts the protrusions. The upper limit of the puncture strength is preferably 45N, more preferably 30N, further preferably 25N. If the thickness is 45N or less, the stiffness of the laminate is not excessively high, and handling is easy. The puncture strength greatly depends on the orientation of the film, and therefore, only by virtue of the change in resin, is not changed so much.

(Heat seal Strength)

The lower limit of the heat seal strength of the laminate of the present invention is preferably 20N/15mm, more preferably 25N/15mm, still more preferably 30N/15mm. If the concentration is 20N/15mm or more, the burst resistance is easily obtained. The heat seal strength is extremely excellent at 60N/15mm, and sufficient at 35N/15 mm.

(packaging body)

The laminate disposed so as to surround the content is referred to as a package for the purpose of protecting the content such as food from dust, gas, and the like in nature. The package can be manufactured by cutting out the laminate, bonding the inner surfaces to each other by a heated heat sealing bar, ultrasonic sealing, or the like, and forming a bag, or the like, and for example, four-side sealed bags in which 2 rectangular laminates are stacked with the sealing layer side inside and four sides are heat-sealed are widely used. The contents may be food, other products such as daily sundries, etc., and the package may have a shape other than square such as a stand-alone pouch or pillow-like package.

The characteristics of the package are described.

(drop-resistant bag breaking Property)

The lower limit of the falling bag breakage resistance of the package formed by using the laminate of the present invention is preferably 12 times or more, more preferably 15 times or more, still more preferably 20 times or more, still more preferably 22 times or more, and particularly preferably 24 times or more. If the number of times is 12 or more, the bag is not easily broken even if the package containing the food is erroneously dropped. The bag-breaking resistance against dropping is sufficient if it is about 30 times.

The package is preferably in a preferable range because the package is affected in resistance to falling and bag breakage by bending pinholes, puncture strength and heat seal strength.

Examples

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto. The characteristics obtained in each example were measured and evaluated by the following methods. In the evaluation, the flow direction of the thin film in the thin film forming step was set to be the longitudinal direction and the direction perpendicular to the flow direction was set to be the width direction.

(1) Resin density

According to JIS K7112: the D method (density gradient tube) in 1999 evaluates density. The average was calculated as measured with n=3.

(2) Melt Flow Rate (MFR)

Based on JIS K-7210-1, the measurement was carried out at 230℃under a load of 2.16kg for propylene-alpha olefin copolymer and propylene homopolymer, and at 190℃under a load of 2.16kg for linear low density polyethylene. The measurement was performed with n=3, and the average value was calculated.

(3) Melting point

The melting point was determined by using the temperature of the maximum melting peak of the DSC curve of the resin obtained by Shimadzu differential scanning calorimeter DSC-60, manufactured by Shimadzu corporation. The starting temperature was set at 30℃and the heating rate was set at 5℃per minute, while the ending temperature was set at 180 ℃. The measurement was performed with n=3, and the average value was calculated.

(4) Haze degree

Haze was measured based on JIS K7136. The polyolefin resin film before lamination was measured at n=3, and the average value was calculated.

(5) Coefficient of static friction

The seal layer sides of the films were overlapped with each other, and measured by a universal tensile tester STM-T-50BP (manufactured by Toyo Baldwin Co., ltd.) in accordance with JIS K7125. The samples were cut into 200mm in the longitudinal direction and 80mm in the width direction by the following 3 methods, and measured.

(6) Young's modulus

Tensile strength in the longitudinal direction and the width direction were measured at 23℃according to JIS-K7127. The Young's modulus (tensile initial elastic modulus) at this time was calculated. The measurement was performed with n=3, and the average value was calculated.

(7) Coefficient of plane orientation

According to JIS K0062: refractive index measurement of chemicals in 1999 evaluate density. The measurement was performed with n=3, and the average value was calculated. The plane orientation coefficient is calculated according to equation 1.

Plane orientation coefficient= (nx+ny)/2-Nz (formula 1)

Nx: refractive index Ny in the longitudinal direction: refractive index Nz in the width direction: refractive index in thickness direction

(8) Wetting tension

The wet tension of the laminate surface was measured according to JIS-K6768 plastic-film and sheet-wet tension test method.

(9) Impact resistance (J)

The measurement was carried out at 23℃using an eastern sperm cell film impact tester.

(10) Accelerated adhesion strength

The polyolefin resin film was cut to a length of 148mm and a width of 105mm. The sealing surfaces are opposed to each other and overlap. After preheating for 30 minutes at 50℃the sheet was clamped by a 7.0cm square aluminum sheet maintained at 50 ℃. The aluminum plate and the sample were pressed at 50℃and 100kN for 15 minutes using Mini test press MP-SCH manufactured by Toyo Seisakusho Co., ltd. The taken sample was cut into 70mm in the width direction. The overlapped samples were opened 30mm and a 3mm diameter metal rod was inserted parallel to the width direction. The sample was mounted on an Autograph AG-I manufactured by Shimadzu corporation, and the weight was measured when the metal rod was moved in the longitudinal direction under the condition of 200 mm/min. The average was calculated as measured with n=3.

(11) Puncture strength

Regarding the polyolefin resin film and the laminate, according to "standard for food, additives, etc. in food sanitation law," 3: appliance and container packaging "(Showa 57. Ministry of thick life, bulletin No. 20," 2. Test method for Strength, etc.), puncture strength was measured at 23 ℃. A needle having a tip end diameter of 0.7mm was made to pierce the film at a piercing speed of 50 mm/min, and the strength of the film when the needle penetrated the film was measured. The measurement was performed with n=3, and the average value was calculated.

(12) Heat seal initiation temperature

The heat seal start temperature of the polyolefin resin film was measured according to JIS Z1713 (2009). At this time, the film was cut into 50mm×250mm (width direction×length direction of the film) rectangular test pieces (for heat sealing). The seal layers were laminated on each other by using a heat-sealing inclination tester (heat-sealing tester) manufactured by Toyo Seiki Seisakusho Co., ltd, so that the heat-sealing pressure was 0.2MPa and the heat-sealing time was 1.0 seconds. Then, heat sealing was performed under conditions of applying each gradient of 5 ℃ and raising the temperature. After heat sealing, the test pieces were cut out at a width of 15 mm. The test piece welded by heat sealing was opened at 180 °, and the unsealed portion was clamped on a chuck to peel off the sealed portion. Then, the temperature at the time when the heat seal strength reached 4.9N was obtained. The tester used was a universal material tester 5965 made of INSTRON INSTRUMENTS. The test speed was set at 200 mm/min. The measurement was performed with n=5, and the average value was calculated.

(13) Pinhole resistance to bending

The laminate having the polyolefin resin film laminated thereon was cut into a length of 280mm and a width of 260mm. Formed such that the polyolefin resin film is insideCylindrical with a height of 260mm, and fixed with cellophane tape. Samples were mounted on a temperature-controlled oven Gelbo Flex Tester manufactured by TESTER SANGYO CO,. LTD. With a bending load applied 1000 times at 1 ℃. The sample was removed and the number of pinholes was determined. The measurement was performed with n=3, and the average value was calculated.

(14) Heat seal strength

The heat sealing conditions and the strength measurement conditions were as follows. That is, the polyolefin resin film sides of the laminate obtained in examples and comparative examples were overlapped with each other, and heat-sealed at a sealing bar width of 10mm and a heat-sealing temperature of 160℃for 1 second under a pressure of 0.2MPa, and then naturally cooled. Test pieces 80mm in the longitudinal direction and 15mm in the width direction were cut from the films heat-sealed at the respective temperatures, and the peel strength at the time of peeling the heat-sealed portions at a crosshead speed of 200 mm/min was measured for each test piece. The tester used was a universal material tester 5965 made of INSTRON INSTRUMENTS. The measurement was performed n=3 times, and an average value was calculated.

(15) Resistance to falling and breaking

The laminate was cut out to prepare a square sealed pouch having an inner dimension of 170mm in the longitudinal direction and 120mm in the transverse direction, in which 200ml of saturated saline was enclosed. The heat-sealing conditions at this time are as follows: the sealing bar width was set to 10mm at a pressure of 0.2MPa for 1 second and the heat sealing temperature was 160 ℃. And cutting off the end part of the square sealing bag after bag making processing, wherein the sealing amplitude is set to be 5mm. Then, the square sealed bag was allowed to stand in an atmosphere at +5℃, and was allowed to fall from a height of 1.2m to a flat concrete floor so that the surface became horizontal for 8 hours. The dropping was repeated until the bag was broken, and the number of repeated dropping was measured. The average was calculated for 20 samples in duplicate.

Example 1

(polyolefin resin film)

The polypropylene resin film of example 1 was prepared from the raw materials based on the resin compositions and the proportions of the respective layers shown in tables 1 and 2 described below. The adjustment in each layer shown in tables 1 and 2 was set to 100 parts by weight, and the mixture was added to the sealing layer as a masterbatch so that 360ppm of behenamide as an organic lubricant and 2000ppm of silica having an average particle diameter of 4 μm as an inorganic anti-blocking agent were obtained. The core layer was charged with 2700ppm of behenamide as an organic lubricant in a masterbatch.

(raw materials used in the sealing layer)

PP-1: sumitomo chemical propylene-ethylene-butene random copolymer FL 6755A (MFR 6.0g/10 min, melting Point 130 ℃ C.)

LL-1: preparation of ethylene-hexene copolymer (Linear Low Density polyethylene of vegetable origin) SLH218 (MFR 2.3 g/min, density 916kg/m by Braskem) ³ Silica particles with melting point 126 ℃): amorphous silica KMP130-4 (average particle size 4 μm) manufactured by Xinyue chemical industry

Organic lubricant: purification of behenamide BNT-22H in Japan

(raw materials used in core layer)

PP-2: sumitomo chemical propylene-ethylene-butene random copolymer FL8115A (MFR 7.0g/10 min, melting point 148 ℃ C.)

PP-3: sumitomo chemical propylene homopolymer FLX80E4 (MFR 7.5g/10 min, melting point 164 ℃ C.)

LL-1: preparation of ethylene-hexene copolymer (Linear Low Density polyethylene of vegetable origin) SLH218 (MFR 2.3 g/min, density 916kg/m by Braskem) ³ LL-2 at melting point 126 ℃): holding the articlesChemical ethylene-hexene copolymer (fossil fuel derived linear low density polyethylene) FV405 (MFR 4.0 g/min, density 923kg/m ³ LDPE-1 with melting point of 118 ℃): preparation of ethylene-hexene copolymer (plant derived Low Density polyethylene) SLH818 (MFR 8.1 g/min, density 918kg/m by Braskem ³ )

Organic lubricant: purification of behenamide BNT-22H in Japan

(raw materials used in laminate layer)

LL-1: preparation of ethylene-hexene copolymer (Linear Low Density polyethylene of vegetable origin) SLH218 (MFR 2.3 g/min, density 916kg/m by Braskem) ³ LL-2 at melting point 126 ℃): sumitomo chemical ethylene-hexene copolymer (fossil fuel derived linear low density polyethylene) FV405 (MFR 4.0 g/min, density 923kg/m ³ LDPE-1 with melting point of 118 ℃): preparation of ethylene-hexene copolymer (plant derived Low Density polyethylene) SLH818 (MFR 8.1 g/min, density 918kg/m by Braskem ³ )

These raw materials were uniformly mixed in the proportions shown in tables 1 and 2 to obtain a mixed raw material for producing a polyolefin resin film.

(melt extrusion)

For the mixed raw materials used in the intermediate layer, a 3-stage single screw extruder having a screw diameter of 90mm was used, and for the mixed raw materials for the heat-seal layer and the laminate layer, a 3-stage single screw extruder having a diameter of 65mm and a diameter of 45mm was used, and the mixed raw materials were introduced into a T-cell die in the order of heat-seal layer/intermediate layer/laminate layer, and the outlet temperature of the die was set at 230 ℃ to perform extrusion, and the T-cell die was designed as follows: the preform section (preform) was divided into 2 stages with a width of 800mm, and the shape of the level difference portion was curved so that the flow of the molten resin became uniform, so that the flow in the mold became uniform. The thickness ratio of the laminate layer/intermediate layer/heat-seal layer was set to 25%/50%/25%, respectively.

(Cooling)

The molten resin sheet from the mold was cooled by a cooling roll at 35℃to obtain an unstretched polyolefin resin film having a thickness of 30. Mu.m. When cooling by the cooling roller, both ends of the film on the cooling roller are fixed by the air nozzle, and the entire width of the molten resin sheet is pressed against the cooling roller by the air knife, and the vacuum chamber is operated to prevent air from being mixed between the molten resin sheet and the cooling roller. For the air nozzle, both ends are arranged in series along the film traveling direction. The mold is surrounded by a sheet around which the molten resin sheet is prevented from being blown by wind. In addition, the direction of the suction port of the vacuum chamber was made to coincide with the traveling direction of the extruded sheet. Further, the mold is surrounded by a sheet around to prevent the molten resin sheet from being blown by wind.

(Corona treatment)

Corona treatment (electric power density of 20 W.min/m) ² )。

(coiling)

The film-forming speed was 20 m/min. The edge portion of the film thus formed is trimmed and wound up in a roll.

(production of laminate)

An ester adhesive having a coating weight of 3.0g/m was obtained by mixing 33.6 parts by mass of a main agent (manufactured by Toyo-Morton Corporation, TM 569) with 4.0 parts by mass of a curing agent (manufactured by Toyo-Morton Corporation, CAT 10) and 62.4 parts by mass of ethyl acetate ² The polyolefin resin films obtained in examples and comparative examples were dry-laminated with a biaxially stretched nylon film (N1102, 15 μm thick, manufactured by Toyo-yo Co., ltd.) as a base film. The wound product was kept at 40℃and cured for 3 days to obtain a laminate.

Example 2

In example 1, a polyolefin resin film was obtained in the same manner as described above except that the raw materials shown in tables 1 and 2 were used so that the thickness of the unstretched polyolefin resin film was 60. Mu.m. A laminate was obtained in the same manner as in example 1.

Example 3 to example 7

In example 1, a 30 μm polyolefin resin film was obtained in the same manner using the raw materials shown in tables 1 and 2. A laminate was obtained in the same manner as in example 1.

(comparative examples 1 to 4 and comparative examples 6 to 7)

Comparative example 5

In example 1, a single-layer 30 μm polyolefin resin film was obtained in the same manner using the raw materials shown in tables 1 and 2 and using an extruder for only the core layer. A laminate was obtained in the same manner as in example 1.

In comparative example 1, since no linear low density polyethylene was added to the core layer and the laminate layer, the bag-breaking resistance by dropping and the pinhole resistance by bending were poor.

In comparative examples 2 and 3, the difference between the linear low-density polyethylene content in the seal layer and the core layer was large, and therefore, the heat seal strength was poor.

In comparative example 4, the content of the linear low density polyethylene in the seal layer was large, and therefore, the heat seal strength was poor.

In comparative example 5, since a large amount of linear low density polyethylene was contained throughout the entire film, a large amount of linear low density polyethylene was contained near the film surface, and the heat seal strength was poor.

In comparative example 6, the core layer contained a linear low density polyethylene, but the laminate layer did not contain a linear low density polyethylene, and therefore the flex pinhole resistance was poor.

In comparative example 7, high pressure Low Density Polyethylene (LDPE) was added as polyethylene, and thus, heat seal strength was poor.

The results are shown in tables 1 and 2.

TABLE 1

TABLE 2

Industrial applicability

According to the present invention, there may be provided: even when laminated with a substrate having high strength such as a biaxially oriented polyamide resin film, a polyolefin resin film having excellent low-temperature sealability, high heat seal strength, and high bag-breaking resistance and pinhole resistance can be greatly contributed to industry.

Claims

1. A polyolefin resin film comprising a polypropylene resin composition containing a propylene-alpha olefin random copolymer,

the polyolefin resin film satisfies the following 1) to 5),

1) Comprising a sealing layer, a core layer and a lamination layer in sequence,

2) The content of the linear low-density polyethylene in the polypropylene resin composition constituting the sealing layer is 3 wt% or less,

3) The content of the linear low-density polyethylene in the polypropylene resin composition constituting the core layer and the laminate layer is 3 to 50 wt%,

4) The difference between the content of the linear low-density polyethylene in the polypropylene resin composition constituting the sealing layer and the core layer is 1 to 18 wt%, the difference between the content of the linear low-density polyethylene in the core layer and the content of the linear low-density polyethylene in the laminate layer is 1 to 18 wt%,

2. The polyolefin-based resin film according to claim 1, wherein the polyolefin-based resin film has a young's modulus in a longitudinal direction and a width direction of 400MPa to 800 MPa.

3. The polyolefin-based resin film according to claim 1 or 2, wherein the thickness of the polyolefin-based resin film is 15 μm or more and 80 μm or less.

4. The polyolefin-based resin film according to any of claims 1 to 3, wherein the linear low-density polyethylene has a density of 910g/m ³ Above and 935g/m ³ The melt flow rate is 2.0g/10 min or more and 7.0g/10 min or less.

5. The polyolefin-based resin film according to any one of claims 1 to 4, wherein the linear low-density polyethylene is a linear low-density polyethylene obtained by polymerizing ethylene containing ethylene derived from a plant.

6. A laminate, comprising: the polyolefin resin film according to any one of claims 1 to 5, and a biaxially oriented polyamide resin film.

7. A laminate, comprising: the polyolefin resin film according to any one of claims 1 to 5, and a biaxially oriented polyester resin film.

8. A package using the laminate according to claim 6 or 7.